Metal oxide, metal bronze and polyoxometalate as charge storage materials in electrochromic device

ABSTRACT

This disclosure relates generally to solution processed low temperature metal oxide, metal bronze or polyoxometalate materials as charge storage material used in electrochromic devices, charge storage material and electrochromic devices comprising the materials and methods of making and using the same.

CROSS-REFERENCE To RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/505,316, filed Jul. 8, 2019, which claims priority to U.S.provisional patent application No. 62/699,382 filed on Jul. 17, 2018,and entitled “Metal Oxide, Metal Bronze and Polyoxometalate as ChargeStorage Materials in Electrochromic Device,” which is incorporatedherein by reference in its entirety.

FIELD

The disclosure relates generally to materials useful for charge storage(or described as counter electrode material) used in electrochromicdevices, charge storage and electrochromic devices comprising thematerials and methods of making and using the same.

BACKGROUND

Electrochromic materials can change the transmittance, reflectance,absorptance or emittance under the action of electrical charge injectionand extraction. The electrochromic films based on flexible substrateshave advantages over the traditional electrochromic glasses in terms ofweight, ease of transportation, ability to apply on curved surface, etc.In typical electrochromic devices, there are three layer of activematerial and two electrodes. Electrochromic layer, electrolyte layer andcharge storage layer are sandwiched in between to transparent electrodesas illustrated in FIG. 1.

A need exists to develop new and/or improved materials for the chargestorage layers, in particular those used in electrochromic films basedon flexible substrates.

SUMMARY

The present disclosure is directed to use of solution processed lowtemperature metal oxide, solution processed low temperature metal bronzeor solution processed low temperature polyoxometalate as a chargestorage material of an electrochromic device. The form of the materialsincluding nanoparticles and films.

The present disclosure is also directed to a charge storage material ofa electrochromic device comprising metal oxide, metal bronze orpolyoxometalate, and a electrochromic device comprising the chargestorage material.

In some embodiments, the metal oxide comprises an oxide of titanium(Ti), vanadium (V), niobium (Nb), zirconium (Zr), molybdenum (Mo),nickel (Ni), copper (Cu) and chromium (Cr), or a mixture thereof. Insome embodiments, metal oxide comprises an oxide of aluminum (Al) orsilicon (Si), or a combination thereof. In some embodiments, the metalbronze is a hydrogen metal oxide wherein the metal is one or more oftitanium (Ti), vanadium (V), niobium (Nb), zirconium (Zr), andmolybdenum (Mo). In some embodiments, the polyoxometalate is aninorganic anion comprising oxygen and a metal such as one or more oftitanium (Ti), vanadium (V), niobium (Nb), zirconium (Zr), andmolybdenum (Mo).

In some embodiments, the metal oxide, metal bronze or polyoxometalate isa hydrate.

In some embodiments, the metal oxide, metal bronze or polyoxometalate isin an amorphous form.

In some embodiments, the metal oxide, metal bronze or polyoxometalate isin nanoparticle form.

In some embodiments, the metal oxide is one or more of

V_(y1)Ti_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:1to about 50:1, y1+y2 is 1,

V_(y1)Si_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:1to about 50:1, y1+y2 is 1,

V_(y1)Al_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:1to about 50:1, y1+y2 is 1,

V_(y1)Mo_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:1to about 50:1, y1+y2 is 1,

V_(y1)Nb_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:1to about 50:1, y1+y2 is 1,

V_(y1)Zr_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:1to about 50:1, y1+y2 is 1,

and V_(y1)Ti_(y2)Al_(y3)O_(x)ωnH₂O, wherein the ratio of y1 to y2 isfrom about 1:1 to about 50:1, the ratio of y2 to y3 is from about 50:1to about 1:50, and the ratio of y1 to y3 is from about 1:1 to about50:1, y1+y2+y3 =1,

and a tri, tetra metal oxide mixture, and its pure form of oxide,

wherein x is from about 2 to about 2.75, and n is from about 0 to about2.

In some other embodiments, the metal oxide is one or more of

V_(y1)Ti_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1, y1+y2 is 1,

V_(y1)Si_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1, y1+y2 is 1,

V_(y1)Al_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1, y1+y2 is 1,

V_(y1)Mo_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1, y1+y2 is 1,

V_(y1)Nb_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1, y1+y2 is 1,

V_(y1)Zr_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1, y1+y2 is 1, and V_(y1)Ti_(y2)Al_(y3)O_(x)⋅nH₂O, whereinthe ratio of y1 to y2 is from about 1:10 to about 50:1, the ratio of y2to y3 is from about 50:1 to about 1:50, and the ratio of y1 to y3 isfrom about 1:10 to about 50:1, y1+y2+y3=1, and a tri, tetra metal oxidemixture, and its pure form of oxide, wherein x is from about 2 to about2.75, and n is from about 0 to about 2.

In still some other embodiments, the metal oxide is one or more of

V_(y1)Ti_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is about 1:2,y1+y2 is 1,

V_(y1)Si_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is about 1:2,y1+y2 is 1,

V_(y1)Al_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is about 1:2 y1+y2is 1,

V_(y1)Mo_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is about 1:2 y1+y2is 1,

V_(y1)Nb_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is about y1+y2 is1,

V_(y1)Zr_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is about 1:2,y1+y2 is 1,

and V_(y1)Ti_(y2)Al_(y3)O_(x)⋅nH₂O, wherein the ratio of y1 to y2 isabout 1:2, the ratio of y2 to y3 is from about 50:1 to about 1:50, andthe ratio of y1 to y3 is about 1:2, y1+y2+y3=1,

and a tri, tetra metal oxide mixture, and its pure form of oxide,

wherein x is from about 2 to about 2.75, and n is from about 0 to about2.

In some embodiments, provided is a method of preparing the metal oxide,metal bronze or polyoxometalate. In some embodiments, the metal oxide,metal bronze or polyoxometalate is prepared from a metal alkoxide. Insome embodiments, the method comprises mixing a metal alkoxide in asolvent such as an alcohol solvent. In some embodiments, the methodfurther comprises coating the solution on a substrate to form a wetlayer, and letting the wet layer dry under ambient conditions to form adried metal oxide layer. In some embodiments, the method furthercomprises drying the dried metal oxide layer at a temperature of belowabout 150° C., to form a high performance charge storage material.

Other objects, features and advantages of the described preferredembodiments will become apparent to those skilled in the art from thefollowing detailed description. It is to be understood, however, thatthe detailed description and specific examples, while indicatingpreferred embodiments of the present invention, are given by way ofillustration and not limitation. Many changes and modifications withinthe scope of the present invention may be made without departing fromthe spirit thereof, and the invention includes all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified schematic illustration of an electrochromicdevice having an electrochromic layer, electrolyte layer and chargestorage layer.

FIG. 2 shows absorption spectra of fully bleached (clear) and reversiblycolorized (opaque) states of an electrochromic device with TiO₂nanoparticles described in Example 1 as the charge storage material,according to some embodiments of the present specification. Filledcircle and empty circle represent absorption spectra of the device inclear state and opaque state, respectively.

FIG. 3 shows absorption spectra of clear state and opaque state of anelectrochromic device comprising a MoO₃ charge storage layer describedin Example 2 as the charge storage material, according to someembodiments of the present specification. Filled circle and empty circlerepresent absorption spectra of the device in clear state and opaquestate, respectively.

FIG. 4 shows absorption spectra of clear state and opaque state of anelectrochromic device comprising a HzMoO_(x) (z is about 2 and x isabout 2 to 4) charge storage layer described in Example 3 as the chargestorage material, according to some embodiments of the presentspecification. Filled circle and empty circle represent absorptionspectra of the device in clear state and opaque state, respectively.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various embodiments of theinvention. However, one skilled in the art will understand that theinvention may be practiced without these details. Moreover, whilevarious embodiments of the invention are disclosed herein, manyadaptations and modifications may be made within the scope of theinvention in accordance with the common general knowledge of thoseskilled in this art. Such modifications include the substitution ofknown equivalents for any aspect of the invention in order to achievethe same result in substantially the same way.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of skill in theart to which this invention belongs.

As used herein, the term “comprising” is intended to mean that thecompositions and methods include the recited elements, but not excludingothers. “Consisting essentially of” when used to define compositions andmethods, shall mean excluding other elements of any essentialsignificance to the combination. For example, a composition consistingessentially of the elements as defined herein would not exclude otherelements that do not materially affect the basic and novelcharacteristic(s) of the claimed invention. “Consisting of” shall meanexcluding more than trace amount of other ingredients and substantialmethod steps recited. Embodiments defined by each of these transitionterms are within the scope of this invention.

Numeric ranges are also inclusive of the numbers defining the range.Additionally, the singular forms “a”, “an” and “the” include pluralreferents unless the context clearly dictates otherwise.

Reference throughout this specification to “one embodiment,” “anembodiment” or “some embodiments” means that a particular feature,structure or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention. Thus,the appearances of the phrases “in one embodiment,” “in an embodiment”or “in some embodiments” in various places throughout this specificationare not necessarily all referring to the same embodiment or embodiments,but may be in some instances. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments.

The term “about” when used before a numerical value indicates that thevalue may vary within reasonable range, such as ±10%, ±5%, and ±1%.

“Alkyl” refers to a straight or branched hydrocarbon chain radicalconsisting solely of carbon (C) and hydrogen (H) atoms, which issaturated or unsaturated (i.e., contains one or more double and/ortriple bonds), having from 1 to 30 carbon atoms (C₁-C₃₀ alkyl), andwhich is attached to the rest of the molecule by a single bond, e.g.,methyl, ethyl, n-propyl, 1-methylethyl (iso-propyl), n-butyl, n-pentyl,1,1-dimethylethyl (t-butyl), 3-methylhexyl, 2-methylhexyl, ethenyl,prop-1-enyl, but-1-enyl, pent-1-enyl, penta-1,4-dienyl, ethynyl,propynyl, butynyl, pentynyl, hexynyl, and the like. Unless statedotherwise specifically in the specification, an alkyl group may beoptionally substituted. In some embodiments, alkyl is a straight orbranched hydrocarbon chain radical having 1 to 20 carbon atoms (C₁-C₂₀alkyl), 1 to 10 carbon atoms (C₁-C₁₀ alkyl), 1 to 6 carbon atoms (C₁-C₆alkyl), or 1 to 4 carbon atoms (C₁-C₄ alkyl).

“Hydrate” refers to a complex formed by combining water molecules withmolecules of a compound, such as a metal oxide, metal bronze orpolyoxometalate.

“Optional” or “optionally” means that the subsequently described eventof circumstances may or may not occur, and that the description includesinstances where said event or circumstance occurs and instances in whichit does not. For example, “optionally substituted alkyl” means that thealkyl radical may or may not be substituted and that the descriptionincludes both substituted alkyl radicals and alkyl radicals having nosubstitution.

In some embodiments, provided herein are metal oxides, metal bronzes orpolyoxometalates prepared under low temperature that are useful ascharge storage materials in electrochromic devices. In some embodiments,the low temperature metal oxides, metal bronzes or polyoxometalates areprepared at a temperature below 150° C. In a flexible electrochromicdevice, processing temperature of all three layers (electrochromiclayer, electrolyte layer and charge storage layer) cannot exceed theglass transition temperature of the plastic substrate materials. In someembodiment, the processing temperature is below 150° C. Providing lowtemperature solution processable materials is crucially important inorder to achieve low cost flexible electrochromic films. Low temperatureprocessable metal oxide, polyoxometalate, or metal bronze as theefficient charge storage materials could significant reduce theprocessing difficulty of a flexible electrochromic device. Further, thematerials are transparent in the visible range and do not exhibit majorcolor changes when changing from clear state to opaque state and viceversa, and therefore they do not interfere significantly with theelectrochromic layer. In some embodiments, the charge storage materialsdescribed herein are at least about 70% transparent in visible lightrange. The transparency measurement may be taken by a minoltaphotospectrometer such as CM-5. In some embodiments, the charge storagematerials described herein are about 70% to 90% transparent. Preparationof such materials avoids use of high temperature or vacuum and thereforecould also reduce the overall cost of the flexible electrochromicproduct.

In some embodiments, the metal oxide is one or more of TiO₂, NiO, Nb₂O₅,WO₃, NiO, V₂O₅, MoO₃, CoO, MoO₂, Ni₂O₃, Co₂O₃, VO_(x), and MoO_(y),etc., wherein x is from about 2 to about 2.5, and y is from about 2 toabout 3, and any mixture from such metal oxide complexes or procurers,or polyoxometalates. In some embodiments, the metal oxides is of theformula M¹ _(y1)M² _(y2)M³ _(y3)O_(x), wherein each M¹, M² and M³ isindependently a metal, such as Ti, Ni, Nb, W, V, Mo, Si, Zr, Al or Co,each y1, y2 and y3 is independently from 0 to 100, provided that atleast one of y1, y2 and y3 is not 0, and x is from 1 to 100. In someembodiments, each y1, y2 and y3 is independently from 0 to 50, or 0 to20, or 0 to 10, provided that at least one of y1, y2 and y3 is not 0. Insome embodiments, x is from 1.5 to 3, each y1, y2, y3 is independently 0to 1, provided that y1+y2+y3 is 1.

In some embodiments, the metal oxide is a hydrate. In some embodiments,the metal oxides is of the formula M¹ _(y1)M² _(y2)M³ _(y3)O_(x)⋅nH₂O,wherein each M¹, M² and M³ is independently a metal, such as Ti, Ni, Nb,W, V, Mo, Si, Zr, Al or Co, x is from 1.5 to 3, each y1, y2 and y3 isindependently from 0 to 1, provided that y1+y2+y3 =1, and n is from0.001 to 3.

In some embodiments, the metal oxide is one or more of

V_(y1)Ti_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1,

V_(y1)Si_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1,

V_(y1)Al_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1,

V_(y1)Mo_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1,

V_(y1)Nb_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1,

V_(y1)Zr_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1,

and V_(y1)Ti_(y2)Al_(y3)O_(x)⋅nH₂O, or other tri, tetra metal oxidemixture, or its pure form of oxide, wherein the ratio of y1 to y2 isfrom about 1:1 to about 50:1, the ratio of y2 to y3 is from about 50:1to about 1:50, the ratio of y1 to y3 is from about 1:1 to about 50:1,

wherein x is from about 2 to about 2.75, y1+y2 is about 1 or y1+y2+y3 isabout 1, and n is from about 0 to about 3. In some embodiments, theratio of y1 to y2 is from about 1:1 to about 40:1, or from about 1:1 toabout 30:1, or from about 1:1 to about 20:1, or from about 1:1 to about10:1, or from about 1:1 to about 5:1, or from about 1:10 to about 50:1,or from about 10:1 to about 50:1, or from about 10:1 to about 40:1, orfrom about 10:1 to about 30:1, or from about 10:1 to about 20:1, or fromabout 20:1 to about 50:1, or from about 20:1 to about 40:1, or fromabout 20:1 to about 30:1, or from about 30:1 to about 50:1, or fromabout 30:1 to about 40:1. In some other embodiments, the ratio of y1 toy2 is about 1:2. In some embodiments, the ratio of y1 to y3 is fromabout 1:1 to about 40:1, or from about 1:1 to about 30:1, or from about1:1 to about 20:1, or from about 1:1 to about 10:1, or from about 1:1 toabout 5:1, or from about 1:10 to about 50:1, or from about 10:1 to about50:1, or from about 10:1 to about 40:1, or from about 10:1 to about30:1, or from about 10:1 to about 20:1, or from about 20:1 to about50:1, or from about 20:1 to about 40:1, or from about 20:1 to about30:1, or from about 30:1 to about 50:1, or from about 30:1 to about40:1. In some other embodiments, the ratio of y1 to y3 is about 1:2. Insome embodiments, the ratio of y2 to y3 is from about 40:1 to about1:50, or from about 40:1 to about 1:40, or from about 40:1 to about1:30, or from about 40:1 to about 1:20, or from about 40:1 to about1:10, or from about 40:1 to about 1:1, or from about 40:1 to about 10:1,or from about 40:1 to about 20:1, or from about 40:1 to about 30:1, orfrom about 30:1 to about 1:50, or from about 30:1 to about 1:40, or fromabout 30:1 to about 1:30, or from about 30:1 to about 1:20, or fromabout 30:1 to about 1:10, or from about 30:1 to about 1:1, or from about30:1 to about 10:1, or from about 30:1 to about 20:1, or from about 20:1to about 1:50, or from about 20:1 to about 1:40, or from about 20:1 toabout 1:30, or from about 20:1 to about 1:20, or from about 20:1 toabout 1:10, or from about 20:1 to about 1:1, or from about 20:1 to about10:1, or from about 10:1 to about 1:50, or from about 10:1 to about1:40, or from about 10:1 to about 1:30, or from about 10:1 to about1:20, or from about 10:1 to about 1:10, or from about 10:1 to about 1:1,or from about 1:1 to about 1:50, or from about 1:1 to about 1:40, orfrom about 1:1 to about 1:30, or from about 1:1 to about 1:20, or fromabout 1:1 to about 1:10, or from about 1:10 to about 1:50, or from about1:10 to about 1:40, or from about 1:10 to about 1:30, or from about 1:10to about 1:20, or from about 1:20 to about 1:50, or from about 1:20 toabout 1:40, or from about 1:20 to about 1:30, or from about 1:30 toabout 1:50, or from about 1:30 to about 1:40.

In some embodiments, the metal bronze (or hydrogen metal oxide bronze)is of the formula H_(z)M¹ _(y1)M² _(y2)M³ _(y3)O_(x), wherein each M¹,M² and M³ is independently a metal, such as Ti, Ni, Nb, W, V, Mo, Si,Zr, Al or Co, each y1, y2 and y3 is independently from 0 to 100,provided that at least one of y1, y2 and y3 is not 0, and each x and zis independently from 1 to 100. In some embodiments, each y1, y2 and y3is independently from 0 to 50, or 0 to 20, or 0 to 10, provided that atleast one of y1, y2 and y3 is not 0. In some embodiments, x is from 1 to10, each y1, y2, y3 is independently 0 to 5, provided that y1+y2+y3 is 1to 5, and z is 1 to 5. In some embodiments, x is from 1.5 to 6, each y1,y2, y3 is independently 0 to 2, provided that y1+y2+y3 is 1 to 3, and zis 1. In some embodiments, the metal bronze is HMoO_(2.4), HMoO_(2.75),HMoO_(2.93), HMoO₃, HV₂O₅, or HVO_(2.46).

Polyoxometalates are polyatomic ions, usually anions. In someembodiments, the polyoxometalate comprises two or more transition metaloxyanions linked together by shared oxygen atoms to form a closed3-dimensional framework. In some embodiments, the polyoxometalatecomprises three or more transition metal oxyanions linked together byshared oxygen atoms to form closed 3-dimensional frameworks. In someembodiments, each metal atom is independently a group 6 (e.g., Mo or W)or group 5 (e.g., V, Nb, or Ta) transition metal. In some embodiments,each metal atom is in its high oxidation state. In some embodiments, thepolyoxometalate is an isopolymetalate, comprising only one kind of metaland oxide. In some embodiments, the polyoxometalate is aheteropolymetalate, comprising one metal, oxide, and a main groupoxyanion (phosphate, silicate, etc.). In some embodiments, thepolyoxometalate is a water-soluble fully inorganic early-transitionmetal-oxygen-anion clusters. In some embodiments, the polyoxometalatecomprises an anion of the formula [A_(s)M¹ _(y1)M² _(y2)M³_(y3)O_(x)]^(m−), wherein A is P or Si, each M¹, M² and M³ isindependently a metal, such as Ti, Ni, Nb, W, V, Mo, Si, Zr, Al or Co,each y1, y2 and y3 is independently from 0 to 100, provided that atleast one of y1, y2 and y3 is not 0, each s and x is independently from1 to 100, and m is an integer of from 1 to 10. In some embodiments, eachy1, y2 and y3 is independently from 0 to 50, or 0 to 20, or 0 to 10,provided that at least one of y1, y2 and y3 is not 0. In someembodiments, one, two or three of y1, y2 and y3 are integers. In someembodiments, A is P. In some embodiments, A is Si. In some embodiments,s is an integer. In some embodiments, s is 1, 2, 3, 4 or 5. In someembodiments, x is from 1 to 70. In some embodiments, x is an integer. Insome embodiments, x is 40 or 62. In some embodiments, m is 1, 2, 3, 4,5, 6, 7 or 8.

In some embodiments, the polyoxometalate comprises [PW₁₂O₄₀]³⁻,[PMo₁₂O₄₀]³⁻, [P₂W₁₈O₆₂]⁶⁻, [P₂Mo₁₈O₆₂]⁶⁻, [Si₂Nb₆W₁₈O₇₇]⁸⁻, or[SiNb₃W₉O₄₀]⁷⁻. In some embodiments, the polyoxometalate furthercomprises a cation, such as H⁺, Li⁺, Na⁺, K⁺, or NH₄ ⁺. Examples ofpolyoxometalates include, but are not limited to, H₃PW₁₂O₄₀, H₃PMo₁₂O₄₀,K₆P₂W₁₈O₆₂, (NH₄)₆P₂W₁₈O₆₂, (NH₄)₆P₂Mo₁₈O₆₂, and H₃PMoO₄₀.

In some embodiments, the metal oxide, metal bronze or polyoxometalate isin an amorphous form.

In some embodiments, provided is a charge storage material of anelectrochromic device comprising a metal oxide, metal bronze orpolyoxometalate. The charge storage material described herein providehigh performance.

In some embodiments, the charge storage material is in the form of alayer of a thin film (charge storage layer) comprising a metal oxide,metal bronze or polyoxometalate and their nanoparticle form describedherein. In some embodiments, the thickness of the film is from about 10nm to about 1000 nm, such as from about 20 nm to about 500 nm, fromabout 20 nm to about 200 nm, or about 20 nm, about 50 nm, about 100 nm,about 150 nm, or about 200 nm, or any range between any two of thenumbers, end points inclusive.

In some embodiments, the charge storage material is in the form ofnanoparticles. In some embodiments, the sizes of the nanoparticles arefrom about 1 nm to about 1000 nm, such as from about 10 nm to about 500nm, from about 20 nm to about 200 nm, or about 10 nm, about 20 nm, about50 nm, about 100 nm, about 150 nm, or about 200 nm, about 250 nm, about500 nm, or any range between any two of the numbers, end pointsinclusive.

The present disclosure is also directed to an electrochromic devicecomprising a charge storage material described herein. Other componentsof electrochromic devices are generally known in the art.

In an electrochromic device, there are two set of materials, anode whichis oxidized while apply positive voltage while driving the device, andcathode which is reducing. The metal oxide, metal bronze orpolyoxometalate described herein can serve as either the anode or thecathode charge storage materials. In some embodiments, the solutionprocessed low temperature metal oxide, metal bronze or polyoxometalatedescribed herein can serve as either the anode or the cathode chargestorage materials. In some embodiments, the electrochromic devicefurther comprises an electrochromic polymer as described in U.S. Pat.No. 9,975,989, which is hereby incorporated by reference in itsentirety.

In some embodiments, the electrochromic device comprising anelectrochromic layer, electrolyte layer and charge storage layer asillustrated by FIG. 1, wherein the charge storage layer comprises themetal oxide, metal bronze or polyoxometalate described herein.

In some embodiments, provided is a method of preparing the metal oxide,metal bronze or polyoxometalate useful as a charge storage material inan electrochromic device. In some embodiments, solution processed lowtemperature metal oxide, metal bronze or polyoxometalate can be used asa charge storage material in an electrochromic device.

Metal oxides could be synthesized prior coating or during the coatingprocess. In some embodiments, the precursor of the metal oxide, metalbronze or polyoxometalate is one or more metal alkoxide. In someembodiments, the metal alkoxide is of the structure M(OR)_(p), wherein Mis a metal, such as Ti, V, Nb, Zr, Mo, Ni, Cu, or Cr, or a mixturethereof, R is an alkyl group, and p is 1, 2, 3, 4, 5, or 6. In someembodiments, the R is C₁-C₄ alkyl, such as methyl, ethyl or isopropyl.

In some embodiments, the method comprises mixing a metal alkoxide in asolvent such as methanol, ethanol, iso-propanol, butanol, methoxyethanolto form a solution or suspension. In some embodiments, the methodfurther comprises coating the solution or suspension on a substrate toform a wet layer. The metal alkoxide hydrolyzes to related metal oxideafter being left under ambient conditions. In some embodiments, themethod further comprises letting the wet layer dry under ambientconditions to form a dried metal oxide layer. In some embodiments, themethod further comprises drying the dried metal oxide layer at atemperature of below about 150° C., to form a charge storage material.In some embodiments, the substrate is a flexible substrate and does nottolerate high temperatures.

In some embodiments, the method comprises forming a solution orsuspension of nanoparticles of a metal oxide in a solvent, such asmethanol, ethanol or isopropanol or water, forming a thin layer of thesolution or suspension and then forming a solid film of the metal oxideby drying the thin layer of the solution or suspension.

In some embodiments, the method comprises oxidizing a metal in asolvent, such as methanol, ethanol or isopropanol, with an oxidationreagent, such as H₂O₂, to form a solution or suspension comprising themetal oxide, metal bronze or polyoxometalate. In some embodiments, themethod further comprises forming a thin layer of the solution orsuspension and then forming a solid film of the metal oxide, metalbronze or polyoxometalate by drying a thin layer of the solution orsuspension.

In some embodiments, the methods described herein do not comprise atemperature that is higher than 150° C. In some embodiments, the methodsdescribed herein are conducted at an ambient temperature.

In some embodiments, provided are metal oxides, metal bronzes orpolyoxometalates prepared by methods described herein which are usefulas charge storage materials of electrochromic devices.

EXAMPLES

The present technology is further defined by reference to the followingexamples. It will be apparent to those skilled in the art that manymodifications, both to compositions and methods, may be practicedwithout departing from the scope of the current disclosure.

Example 1 Titanium Oxide

Such oxide material could be pre-synthesized, like TiO₂ nano-crystals,and dissolved or dispersed in a proper solvent. For example, 5 nm to 15nm anatase TiO₂ nano-crystal dispersion in water was diluted into 10mg/mL concentration. The solution was dispersed with a slot die coaterto form a thin uniform film with 20 micrometer thick liquid layer. Theresulted dried TiO₂ solid layer is about 200 nm thick. Such thin layercould be served as charge storage layer in cathode with anelectrochromic polymer material as the anode. The electrolyte wasdescribed in US2017/0299932, which is hereby incorporated by referencein its entirety. The electrochromic polymer could be fully bleached at2.1 V, and reversibly colorized at −1.0V. The absorption spectra of thetwo states are shown in FIG. 2.

Example 2 Molybdenum Oxide

Metal oxide complex could be also formed during the film formation viareaction such as hydrolysis process. Mo(OC₂H₅)₅ with 1% weight ratio inethanol was applied by a slot die coater, and form a solid film. Thefilm was baked and assembled with an electrochromic polymer andelectrolyte (e.g., those described in US2017/0299932) to form an activeelectrochromic device. Such device could be switched between opaque andclear with 1.5 V and −1 V. The absorption spectra are shown in FIG. 3.

Example 3 Polyoxometalate

Metal oxide or polyoxometalate could be synthesized as the metal bronzeor solution. 1 g of Mo was added to 100 mL ethanol and then 3 mL of 30%H202 was added. The mixture was stirred overnight in room temperature toresult a dark blue metal bronze solution. The solution was applied via aslot die coater to form a 100 nm solid film, the composition of suchmetal bronze material is suggested to be HyMoOx. Such film was assembledwith electrochromic polymer and electrolyte to form an active device.Such device could be switched reversibly with 1.2V to −1V. Theabsorption spectra were shown in FIG. 4.

Applications/Uses

Embodiments of the charge storage materials comprising metal oxide,metal bronze or polyoxometalate disclosed herein may be used in variousapplications, devices, industries etc. For example, the charge storagematerials may be configured for use in smart window and displaytechnology, e.g., anti-glare car mirrors, smart windows configured tomodulate the transmission or reflected solar radiation for use in cars,aircrafts, buildings, and the like; protective eyewear; camouflageand/or chameleonic materials; and other electrochromic devices.

The invention described and claimed herein is not to be limited in scopeby the specific preferred embodiments disclosed herein, as theseembodiments are intended as illustrations of several aspects of theinvention. Indeed, various modifications of the invention in addition tothose shown and described herein will become apparent to those skilledin the art from the foregoing description. Such modifications are alsointended to fall within the scope of the appended claims.

What is claimed is:
 1. A charge storage material of an electrochromicdevice comprising one or more of: a metal oxide of a formula M¹ _(y1)M²_(y2)M³ _(y3)O_(x) or a hydrate thereof of a second formula M¹ _(y1)M²_(y2)M³ _(y3)O_(x)⋅nH₂O, wherein: M¹, M² and M³ are different metals, xis from 1.5 to 3, each y1, y2 and y3 is independently from 0 to 1,y1+y2+y3 is 1, and n is independently from 0 to 3; and a metal bronze ofa third formula H_(z)M¹ _(y1)M² _(y2)M³ _(y3)O_(x), or a hydratethereof, wherein: M¹, M² and M³ are different metals, each y1, y2 and y3is independently from 0 to 100, at least one of y1, y2 and y3 isnonzero, and each of x and z is from 1 to
 100. 2. The charge storagematerial of claim 1, comprising the hydrate of the metal oxide, thehydrate being selected from: V_(y1)Ti_(y2)O_(x)⋅nH₂O wherein the ratioof y1 to y2 is from about 1:10 to about 50:1, V_(y1)Si_(y2)O_(x)⋅nH₂Owherein the ratio of y1 to y2 is from about 1:10 to about 50:1,V_(y1)Al_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1, V_(y1)Mo_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 isfrom about 1:10 to about 50:1, V_(y1)Nb_(y2)O_(x)⋅nH₂O wherein the ratioof y1 to y2 is from about 1:10 to about 50:1, V_(y1)Zr_(y2)O_(x)⋅nH₂Owherein the ratio of y1 to y2 is from about 1:10 to about 50:1, andV_(y1)Ti_(y2)Al_(y3)O_(x)⋅nH₂O, wherein the ratio of y1 to y2 is fromabout 1:10 to about 50:1, the ratio of y2 to y3 is from about 50:1 toabout 1:50, and the ratio of y1 to y3 is from about 1:10 to about 50:1,or mixture thereof, wherein: x is from about 1.5 to about 3, y1+y2 is 1or y1+y2+y3 is 1, and n is from about 0 to about
 3. 3. The chargestorage material of claim 1, wherein the charge storage material has atransparency of about 70% to about 90% within a visible spectrum, withinwhich wavelengths range from between about 380 nm to about 700 nm. 4.The charge storage material of claim 1, wherein each M¹, M² and M³ isselected from Ti, Ni, Nb, W, V, Mo, Si, Zr, Al or Co.
 5. The chargestorage material of claim 1, comprising the metal bronze, the metalbronze being selected from HMoO_(2.4), HMoO_(2.75), HMoO_(2.93), HMoO₃,HV₂O₅, or HVO_(2.46).
 6. The charge storage material of claim 1, whereinthe charge storage material comprises a thin film of between about 20 nmto about 200 nm or nanoparticles of between about 20 nm to about 200 nmin diameter.
 7. The charge storage material of claim 1, wherein thecharge storage material comprises a polyoxometalate.
 8. Anelectrochromic device comprising: a charge storage material comprisingone or more of: a metal oxide of a formula M¹ _(y1)M² _(y2)M³ _(y3)O_(x)or a hydrate thereof of a second formula M¹ _(y1)M² _(y2)M³_(y3)O_(x)⋅nH₂O, wherein: M¹, M² and M³ are different metals, x is from1.5 to 3, each y1, y2 and y3 is independently from 0 to 1, y1+y2+y3 is1, and n is independently from 0 to 3; and a metal bronze of a thirdformula H_(z)M¹ _(y1)M² _(y2)M³ _(y3)O_(x), or a hydrate thereof,wherein: M¹, M² and M³ are different metals, each y1, y2 and y3 isindependently from 0 to 100, at least one of y1, y2 and y3 is nonzero,and each of x and z is from 1 to
 100. 9. The electrochromic device ofclaim 8, wherein the charge storage material comprises the hydrate ofthe metal oxide, the hydrate being selected from:V_(y1)Ti_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1, V_(y1)Si_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 isfrom about 1:10 to about 50:1, V_(y1)Al_(y2)O_(x)⋅nH₂O wherein the ratioof y1 to y2 is from about 1:10 to about 50:1, V_(y1)Mo_(y2)O_(x)⋅nH₂Owherein the ratio of y1 to y2 is from about 1:10 to about 50:1,V_(y1)Nb_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 is from about 1:10to about 50:1, V_(y1)Zr_(y2)O_(x)⋅nH₂O wherein the ratio of y1 to y2 isfrom about 1:10 to about 50:1, and V_(y1)Ti_(y2)Al_(y3)O_(x)⋅nH₂O,wherein the ratio of y1 to y2 is from about 1:10 to about 50:1, theratio of y2 to y3 is from about 50:1 to about 1:50, and the ratio of y1to y3 is from about 1:10 to about 50:1, or mixture thereof, wherein: xis from about 1.5 to about 3, y1+y2 is 1 or y1+y2+y3 is 1, and n is fromabout 0 to about
 3. 10. The electrochromic device of claim 8, whereinthe charge storage material has a transparency of about 70% to about 90%within a visible spectrum, within which wavelengths range from betweenabout 380 nm to about 700 nm.
 11. The electrochromic device of claim 8,wherein each M^(l), M² and M³ is selected from Ti, Ni, Nb, W, V, Mo, Si,Zr, Al or Co.
 12. The electrochromic device of claim 8, wherein thecharge storage material comprises the metal bronze, the metal bronzebeing selected from HMoO_(2.4), HMoO_(2.75), HMoO_(2.93), HMoO₃, HV₂O₅,or HVO_(2.46).
 13. The electrochromic device of claim 8, wherein thecharge storage material comprises a thin film of between about 20 nm toabout 200 nm.
 14. The electrochromic device of claim 8, wherein thecharge storage material comprises nanoparticles of between about 20 nmto about 200 nm in diameter.
 15. The electrochromic device of claim 8,wherein the charge storage material is disposed at an anode of theelectrochromic device.
 16. The electrochromic device of claim 8, whereinthe charge storage material is disposed at a cathode of theelectrochromic device.
 17. The electrochromic device of claim 8, furthercomprising π-conjugated chromophores, wherein at least one of theπ-conjugated chromophores is separated by a spacer.
 18. Theelectrochromic device of claim 17, wherein the π-conjugated chromophoreare colored in a neutral state, and colored or transmissive in anoxidized state.
 19. The electrochromic device of claim 8, furthercomprising a solid polymer electrolyte comprising an inorganic salt,wherein the solid polymer electrolyte is devoid of liquid or gelcomponents.
 20. The electrochromic device of claim 8, further comprisinga polymer matrix comprising one or more polar polymers that comprise asemi-crystalline or crystalline microstructure.